The objective of this study is to investigate the effects of the uncertainties of major modelling parameters on the bridge seismic response. The parameters examined include the superstructure mass, concrete compressive strength, plastic hinge length and damping. For the purpose of the evaluation, an existing 3-span reinforced concrete highway bridge located in Montreal, Canada, was selected for the analysis. A three-dimensional model of the bridge was developed using SAP2000. Nonlinear time-history analyses were conducted in order to assess the effects of the uncertainty of each of modelling parameters mentioned above. Fifteen records obtained from earthquakes around the world were used as seismic excitations in the time-history analysis. The deck displacement and the column curvature ductility were chosen to investigate the effect of the uncertainty of the modelling parameters on the seismic response of the bridge.